LIGHT FROM A LAND OF DARKNESS

Ashburton Guardian, Volume VII, Issue 1721, 28 November 1887, Page 4

LIGHT FROM A LAND OF DARKNESS

It is curious that a valuable photographic invention should come from the borders of civilisation — Rutsia. Photcgraphio etchlcg upon boxwood blocks, such ac are ÜBed In wood engraving, has been deemed a practical impossibility. We leera, however, that it has recently been accomplished tn Rusda, and by a method eimple and ingenious. The block m ita natural condition, is, of course, unsuitable. The first etep is to fill ita porea with insoluble oarbocatetf copper by means of tsro separate solutions, m,, which ft fo botfed suffiaienily. A poliih is then Imparted tp Ha. «uff*ce, asphalte m solution applied to its back and aides, and finally A-eetisitive gelatine film placed over tho poliebel fa.2B. The eubject to be etched is now photographed on the surface, and, by washing the soluble and anprinted parts of the gelatine Is removed A coating of asphalts is next appled to the raised parts, tbe block eteeped m nitric acid of suitable strength (the atrongor the better), where it remairs oce hour, ffhen it is removed and subjected to the action cf aulphanc acid for the same time. The portions unprotected are thus changed to nitro-celloloße, which, by brushing, is readily removed m the form, of a greet ish powder. To complete the pruceos, the Hock ia dried and brlakly brushed with a stiff brush. The aaphalte ia lastly rr moved with betz^ne. and the block ia ready for the preee. The ptrctloal valne aa to depth aDd retention of details we cannot state. It ia an innovation, however, that may prove worthy of attention